Lecture Notes: The Brain

Main Regions of the Brain

• Cerebrum
  • Largest portion; associated with higher functions such as thought and action.
  • Often what people visualize when they think of the brain.
• Diencephalon
  • Located deep within the brain.
• Brain Stem
  • Connects the brain to the spinal cord.
• Cerebellum
  • Located posteriorly and inferiorly; involved in motor control.
  • Smaller than the cerebrum.

Protection of the Brain

• Cranial Bones
  • Strong bones surrounding the brain.
• Meninges
  • Three layers: dura mater, arachnoid mater, pia mater.
  • Protects CNS (Central Nervous System).
• Spaces Between Meninges
  • Epidural space: Between bone and dura mater.
  • Subdural space: Between dura mater and arachnoid mater.
  • Subarachnoid space: Contains cerebrospinal fluid (CSF).

Cerebrospinal Fluid (CSF)

• Colorless fluid circulating in ventricles and subarachnoid space.
• Functions: buoyancy, protection, nutrient transport.

The Ventricles

• Cavities within the brain that are filled with CSF.
• Lateral ventricles: One in each hemisphere.
• Third ventricle: Connected to lateral ventricles via interventricular foramen.
• Fourth ventricle: Connected to third via cerebral aqueduct.

Cerebrum Structure

• Hemispheres: Left and right, connected by the corpus callosum.
• Lobes: Frontal, parietal, temporal, occipital.
  • Frontal: Voluntary movement, planning, personality.
  • Parietal: Sensory perception.
  • Temporal: Hearing, smell.
  • Occipital: Vision.
• Gyri and Sulci: Folds and grooves that increase surface area.
• Gray and White Matter: Gray on the outside (cerebral cortex), white deeper.

Functional Areas of the Cerebrum

• Motor Areas: Control voluntary movements; found in the frontal lobe.
  • Primary Motor Cortex: In precentral gyrus.
• Sensory Areas: Receive and interpret sensory impulses.
  • Primary Sensory Cortex: In postcentral gyrus; for touch, temperature, pain.

Diencephalon Components

• Thalamus: Relay station for sensory and motor signals.
• Hypothalamus: Regulates autonomic nervous system and endocrine system.
• Epithalamus: Contains the pineal gland, which secretes melatonin.

Brain Stem

• Midbrain: Vision and auditory reflexes.
• Pons: Connects different parts of the brain.
• Medulla Oblongata: Heart rate, breathing, reflexes.

Cerebellum

• Coordination: Fine-tunes motor activity; involved in balance and equilibrium.
• Structured with layers called folia.

Limbic System

• Processes emotions.
• Includes structures such as the hippocampus (memory) and amygdaloid body (emotion).

Higher Order Brain Functions

• Include learning, memory, reasoning.
• Located mainly in the cerebral cortex but involve multiple brain regions.